Wednesday, October 31, 2007

Over at the Mind blog, Deric has just posted a very fascinating exchange of opinions amongst Christof Koch and Susan Greenfield regarding the neural correlates of consciousness. the exchange seems to be from Scientific American, and in it both Christof and Susan put forward their views on the NCC and then have minor quibbles over particular conscious experiences / phenomenon. While Koch believes that consciousness of a percept arises from activation of a unique set of neurons, that form assemblies and networks and the neurons themselves differ from normal neurons (he implicates a strong role for layer 5 pyramidal neurons in Frontal cortex, having synapses with occipital visual areas, as being crucial for a conscious percept) , Susan insists that consciousness arises because of synchronous firing of neuronal assemblies - and the degree of consciousness depends on the number of neurons involved in that synchronous assembly (that lats up to millisecond intervals) . Thus while Koch focuses more on content of consciousness (and despite Susan's criticism that is an important area of investigation) and how it arises from a qualitative phenomenon (different types of neurons - pyramidal- involved), Susan focuses more on degrees of consciousness and takes consciousness to be a qualitative phenomenon. I, like Deric , find merit in both arguments.

Some excerpts:

Koch's view:

Physiologically, the likely substrate for NCC is a coalition of pyramidal neurons--a type of neuron that communicates over long ranges--within the cerebral cortex. Perhaps only a million such neurons--out of the 50 billion to 100 billion in our heads--are needed to form one of these coalitions. When, say, Susan enters a crowded room and I see her face, a coalition of neurons suddenly chatters in concert for a fraction of a second or longer. The coalition reaches from the back of the cortex, where representations of visual stimuli are first processed, into the front of the cortex, which carries out executive functions such as providing perspective and enabling planning. Such a coalition would be reinforced if I paid attention to the stimulus of her image on my retina, which would strengthen the amplitude or the synchrony of the activity among the select neurons. The coalition sustains itself and suppresses competing coalitions by feeding excitatory signals back and forth among the neurons in the back and front of the cortex. If, suddenly, someone calls my name, a different coalition of neurons in the auditory cortex arises. This coalition establishes two-way communication with the front of the brain and focuses my consciousness on the voice, suppressing the earlier coalition representing Susan's face, which fades from my awareness.

This notion about networks of neurons has received a boost from recent results by researchers at the Mount Sinai School of Medicine, Columbia University and the New York State Psychiatric Institute, working under Stuart C. Sealfon of Mount Sinai and Jay A. Gingrich of Columbia. Sealfon's and Gingrich's teams have demonstrated in genetically modified mice that hallucinogens--such as LSD, psilocybin (an ingredient of mushrooms) and mescaline--act on a type of molecule, called a serotonin receptor, found on the pyramidal cells that cluster in layer 5. The hypothesis that the mind-bending effects of hallucinogenic compounds come from activation of one receptor type on a specific set of neurons--rather than from "messing up" the brain's circuits in some holistic manner--can be further tested with molecular tools that can toggle layer 5 pyramidal cells on and off until the exact set of neurons being affected is identified.

Susan's views:

My own starting assumption is that there is no intrinsic, magical quality in any particular brain region or set of neurons that accounts for consciousness. We need to identify a special process within the brain. And to be a truly robust correlate of consciousness, this neuronal process must account for a variety of everyday phenomena, including the efficacy of an alarm clock, the action of anesthetics, the distinction of dreams from wakefulness, the existence of self-consciousness, the possible difference between human and animal consciousness, and the possible existence of fetal consciousness. A more plausible view of consciousness is that it is not generated by a qualitatively distinct property of the brain but by a quantitative increase in the holistic functioning of the brain. Consciousness grows as brains grow.

The central problem is that models developed by Llinas and others conceive of consciousness as an all-or-nothing condition. They fail to describe how the physical brain can accommodate the ebb and flow of a continuously variable conscious state. I favor an alternative. For more than a decade, scientists have known that the activity of tens of millions of neurons can synchronize for a few hundred milliseconds, then disband in less than a second. These "assemblies" of coordinating cells can vary continuously in just the right space and timescales for the here-and-now experience of consciousness. Wide-ranging networks of neurons assemble, disassemble and reassemble in coalitions that are unique to each moment. My model is that consciousness varies in degree from one moment to the next and that the number of neurons active within an assembly correlates with the degree of consciousness present at any given time.

This neuronal correlate of consciousness--the transient assembly--satisfies all the items on the shopping list of phenomena above. The efficacy of an alarm clock is explained as a very vigorous sensory input that triggers a large, synchronous assembly. Dreams and wakefulness differ because dreams result from a small assembly driven by weak internal stimuli, whereas wakefulness results from a larger assembly driven by stronger external stimuli. Anesthetics restrict the size of assemblies, thus inducing unconsciousness. Self-consciousness can arise only in a brain large and interconnected enough to devise extensive neuronal networks. The degree of consciousness in an animal or a human fetus depends on the sizes of their assemblies, too.

Take a look at the original debate as there is an even more more stimulating point-counterpoint section too.
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Tuesday, October 30, 2007

In a recent article, Kounios, J., et al., The origins of insight in resting-state brain activity, Neuropsychologia (2007), it has been shown that creative thinking style , associated with an 'AHA' moment of problem-solving using insight, deploys more Right brain areas and also is characterized by a more diffused visual attention; as compared to an analytic style , which used search as a strategy and was characterized by more focussed visual attention.

As I had been linking to some articles on brain asymmetry , I found this article worth linking to. The paper basically uses self-report measures to ascertain whether an anagram ( scrambled words like XPELAME for EXAMPLE) was solved by creative insight or by analytic search. It then divided the subjects into two groups- those utilizing insight as a strategy most of the time and those utilizing search as a strategy most of the time. then they looked at the EEG activations, both prior to the assignment (when the subjects were not even aware of the purpose of the study) and while the people solved the anagrams. The first EEG measure that refers to the resting style of a person, showed clear differences between the two groups. It was found that the creatives or insight people had more diffused visual attention, while the analytic searchers had more center-increase/surround-decrease type of cortical activity whihc would be correlated with more focused attention, in both visual areas as well as semantical areas. The creatives on the other hand, had resting EEG that implicated more loose semantic associations at the periphery.

The second interesting result was regarding the overall activation of right hemisphere versus left hemispheres in the creative vs analytic groups. Here again, High Insight group showed more right Hemisphere activations across many regions of interest and on many bands (alpha, gamma etc) of EEG frequencies.

I had approached the paper with a critical bent of mind as soon as I read that they had used self-reports, but it seems that they could find some indirect evidence as to whether the self-report measure styles did correspond to the actual styles employed. They reason, and show, that if a problem is being solved by insight, then the solution would be available in a a one-or-nothing sort of consciousness of the solution; hence the creatives would do more errors of omission, where they would timeout when given a deadline to solve the problem; on the other hand the analytics would be solving the problem in a piece-meal fashion, with the solution being formed bit-by0-bit in their consciousness and are thus more likely to do acts of commissions, where when confronted with a deadline, they give a wrong response. this is exactly what they found, moreover there was no differences in response times, error rate or any other measures that could have explained things otherwise, and I find their argument convincing.

The present study demonstrates that goal-oriented, event related,cognitive processing is not completely determined by goals or task demands. Individual differences in resting state brain activity also influence such neural computations. Specifically, subjects’ preferred strategy for solving a series of anagrams (insight versus search), was influenced by characteristics of their prior resting state. This phenomenon is fundamentally different from the previous demonstration of a relationship between problem-solving strategy and transient preparatory activity immediately preceding the presentation of an anticipated problem .

The results were organized around two hypotheses. The first was based on previous research demonstrating that highly creative individuals exhibit diffuse attention allowing input of a greater range of environmental stimuli, in contrast to less creative individuals who tend to focus their attention more narrowly, thereby sampling a smaller range of environmental stimuli . It was therefore predicted that HI subjects would have less resting-state occipital alpha-band activity, reflecting less inhibition of the visual system, and that LI subjects have more occipital beta activity, consistent with heightened focused attention. These predictions were supported by the results.

The second hypothesis was that HI and LI subjects would exhibit different patterns of resting-state hemispheric asymmetry at electrodes over lateral association cortex. This hypothesis was based on prior findings that creative cognition recruits RH association areas involved in semantic information processing relatively more than does noncreative cognition . The results provided broad support for the hypothesis that during a resting state HI subjects would show generally greater RH activity and less LH activity relative to LI subjects, with the most prominent effects being greater activity for HI subjects at right dorsal–frontal (lowalpha band), right inferior–frontal (beta and gamma bands) and right parietal (gamma band) electrodes, and greater activity at left inferior–frontal and left anterior–temporal electrodes for LI subjects in the low-alpha band.

Importantly, the behavioral results demonstrated that the HI and LI groups used different cognitive strategies to solve the anagrams. Consistent with the notion that insight processing yields information about the correct response in a discrete, all-or-none, fashion, while noninsight processing yields partial response information before the processing of a problem has been completed , the present results showed that subjects who tended to solve problems with self-reported insight tended to make errors of omission, while subjects who tended to solve the problems with self-reported noninsight processing tended to make errors of commission.

As such, I am excited by this research which adds not only to our understanding of the 'insight' problem solving, but also adds to the knowledge base on brain asymmetry.
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Monday, October 29, 2007

Over at the Health Information blog, they have just posted 5 articles (mostly form other sources on the net) regarding the left brain/ right brain asymmetry debate.

I, in particular, liked the article by Gazzaniga, in which he discusses amongst other things the confabulaory nature of left hemisphere 'interpreter' or 'narrator'. Another article I liked was by John McCrone and focussed more on the global versus Local style of processing style differences amongst the two hemispheres. Head over and have a read. I myself have strong opinions about the asymmetry and specialization and would like to see gender differences too taken in account, as I believe Men and Women do use different processing styles and this may have to do with using the hemispheres differently.

As expected, the video is a treat for anyone interested in the human brain. Ramachandran touches on his pet topics like the explanations for Capgras delusion ( a disconnect between the regions that recognize a face visually, and that endow that face with emotional significance) , the cure for phantom limbs (including not only making the phantom disappear using a 6 $ mirror box, but also making the phantom pain disappear (for whihc I hope he does get a Noble prize!!)) and synaesthesia (which he relates to creativity). As usual, an excellent talk and definitely worth watching. Thanks, Natasha!!

Just to recap, I believe in a 5 +3 = 8 step development/ evolutionary model, wherein the first 5 stages are qualitatively different from the last 3 ; but the stages of development / evolution are analogous in widely different faculties.

thus, I was quite surprised to discover a model of Consciousness, as proposed by Timothy Leary, that I was till now not aware of . Thanks to Mind Hacks, I spent a better part of my day on the net reading about Leary's and RAW, eight circuit theory and I find it quite plausible and fascinating. Some linksworthchecking.

Although I do not buy the left-brain/ right-brain distinction in totality, I do find the fact that the first five stages are related to embodied consciousness, while the last three mark a departure and closely parallel other higher level stages quite interesting.

The evolutionary and developmental stages of Leary are :

I. THE BIO-SURVIVAL CIRCUIT

The imprinting of this circuit sets up the basic attitude of trust or suspicion which will ever after trigger approach or avoidance

This is clearly the trust vs distrust development task identified by Erikson for infants. Leary though applies it to the living race (invertebrates ) on an evolutionary scale.

II. THE EMOTIONAL CIRCUIT

Again the first imprint on this circuit remains constant for life (unless brainwashed) and identifies the stimuli which will automatically trigger dominant, aggressive behavior or submissive, cooperative behavior.

This maps closely to Erikson's second toddler stage, whereby the toddler has to master Autonomy (a sense of power) vs Shame and Doubt

III. THE DEXTERITY-SYMBOLISM CIRCUIT

It is no accident, then, that our logic (and our computer-design) follows either-or, binary structure of these circuits

The fourth brain, dealing with the transmission of tribal or ethnic culture across generations, introduces the fourth dimension, time.

This is the traditional Social background process, stretched over the whole school life of the child, wherein he develops a sense of industry and a sense of skills that can be refined with hard work over time. Time if of essence here.

V. THE NEUROSOMATIC CIRCUIT

When this fifth "body-brain" is activated, flat Euclidean figure-ground configurations explode multi-dimensionally. Gestalts shift, in McLuhan's terms, from linear VISUAL SPACE to all-encompassing SENSORY SPACE. A hedonic turn-on occurs, a rapturous amusement, a detachment from the previously compulsive mechanism of the first four circuits.

The fifth stage is a transforming stage that enables a rite of passage. In Erikson.s model it is transcendence of adolescence and taking on an adult role. One solves the problem of Identity vs Role Confusion. In my view this stage is also linked to Schizophrenia , which may result from role confusions and results in hallucinations. It is orthwhile to note here that many hallucinogens, as per Leary, lead to this stage.

VI. THE NEUROELECTRIC CIRCUIT

The sixth brain consists of the nervous system becoming aware of itself apart from imprinted gravitational reality-maps (circuits I-IV) and even apart from body-rapture (circuit V).The evolutionary function of the sixth circuit is to enable us to communicate at Einsteinian relativities and neuro-electric accelerations, not using third circuit laryngeal-manual symbols but directly via feedback, telepathy and computer link-up. Neuro-electric signals will increasingly replace "speech" (hominid grunts) after space migration.

This meeting and communication between inter-stellar civilizations, bodes well on a human level with Erikson's marriage as the sixth developmental milestone with Intimacy vs Isolation as a core developmental task

VII. THE NEUROGENETIC CIRCUIT

The seventh brain kicks into action when the nervous system begins to receive signals from WITHIN THE INDIVIDUAL NEURON, from the DNA-RNA dialogue. The first to achieve this mutation spoke of "memories of past lives," "reincarnation," "immortality," etc. The "akashic records" of Theosophy, the "collective unconscious" of Jung, the "phylogenetic unconscious" of Grof and Ring, are three modern metaphors for this circuit.

this also bodes well with the collectivist nature of Erikson's seventh developmental task, wherein , as a group of individual (member of society) one feels Generativity vs Stagnation.

VIII. THE NEURO-ATOMIC CIRCUIT

When the nervous system is turned on to this quantum-level circuit, space-time is obliterated. Einstein's speed-of-light barrier is transcended; in Dr. Sarfatti's metaphor, we escape "electromagnetic chauvinism." The contelligence within the quantum projection booth IS the entire cosmic "brain," just as the micro-miniaturized DNA helix IS the local brain guiding planetary evolution. As Lao-tse said from his own Circuit VIII perspective, "The greatest is within the smallest."

This too bodes well as the eights stage again being the ultimate stage of transcendence, coming to terms with one's inevitable (human) death and either having Integrity vs Despair as one reflects on life and prepares to transcend it

I know that a lot of the above my sound nonsensical to the regular readers of this blog, but we know so little about consciousness, that it may be best to keep an open mind about it and about evolution and our fate as human race.

Thursday, October 11, 2007

For some time, I have been toying with the idea of having a one-stop online question bank for psychology and Neuroscience. I believe, that if one answers a few questions, after reading about the topic on the web, then the process of answering questions makes the learning more effective and the memory trace more permanent.

I, myself, have learned, much from the net and Wikiquest is my way of putting together a tool that may help generate a comprehensive question bank of topics related to psychology and Neuroscience. I have adopted a wiki model as it gives each of the participants equal opportunity to contribute , both towards questions, as well as towards rectifying errors or adding better explanations.

The way Wikiquest works is intuitive. I have put together a few questions there as a pilot test. These can be accessed via a tag cloud on the left hand side. Just click on the topic of your choice and that will take you to a page that contains links to the actual question pages. the actual question pages should not be scrolled down fast as they have the hints and answers too on the same page. You are encouraged to edit information , if you think it is misleading, incorrect. You are also encouraged to add questions, either original, or from some other non-licensed content on the web.

I do hope that like other Psychology based initiatives like PsychAntenna , this too catches up and we get a good online question bank, which proves to be a valuable learning resource based on the knowledge and wisdom of the masses.

For those of you who have blogs, a blog post regarding WikiQuest would be hugely appreciated.

Wednesday, October 10, 2007

I recently came across an economist article that pointed to me three new studies regarding fairness, patience and their genetic and evolutionary footprints.

From one of the studies, conducted by Wallace it al, a counterintuitive result is obtained- that a sense of fairness (as measured by propensity to share and reject low offers in the ultimatum game) is very much heritable with Monozygotic twins showing a positive correlation between their propensities to respond in the ultimatum game as compared to Dizygotic twins, who show no such correlation. This seems to strongly support the view that our sense of Altruism (dependent on our willingness to punish free-loaders) and fairness is genetic to a large extent. with the evolutionary explanations of Altruism depending heavily on the punishment arguments, it is not so surprising to find that a sense of fairness is indeed genetic in nature; but for many culture enthusiasts, this would come as a blow to their view that Altruism did not evolve, but is a product of uniquely human endeavor called culture.

Another article looks at the sense of fairness itself , again using the ultimatum game, and compares between humans and chimps. while it is well-know that humans have a snese of fairness and thus make equitable offers and reject low offers, no data on chimps was available till now. It seems Chimps are more rational and unemotional than humans!

To find out if chimpanzees share this sense of fairness, Keith Jensen and his colleagues at the Max Planck Institute for Evolutionary Anthropology, in Leipzig, designed a way for chimps to play the ultimatum game. Their version started with a pair of trays far from the players' cages. Each tray had ten raisins divided in different ways between two pots—say eight and two, or five and five. One chimp was allotted the role of proposer. He could choose one of the trays, pulling it by way of a rope just halfway to the cage. The other, the responder, could then choose to pull on a rod, bringing the tray close enough for both to get the raisins, one pot for each. If the responder chose not to pull the tray closer within a minute, the offer was considered rejected, and the game concluded.

The result, which Dr Jensen reports in Science, is that chimps are simply rational maximisers—Pan economicus, if you like. Though proposers consistently chose the highest possible number of raisins for themselves, responders rarely rejected even the stingiest offers.

I would like to see the same replicated with bonobos. Do they too lack a sense of fairness and whatever co-operation has been observed in them simply a result of free-sex-trade?

The third article actually looked at difference between patience and fairness in chimps and humans and gain came to a very counter-intuitive results. Chimps can be more patient than humans and delay gratification at more occasions than humans. Clearly their sense of prospection is better developed than Humans (which I doubt) , or they are unemotional and hence lack the normal human dread of waiting for a result of something (even positive). In any case some really important results and papers.
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the 33rd edition of neuroscience carnival encephalon is now online. A couple of my favorites include the review of "The Body has a Mind of its own" and a post on the lateral asymmetry in brains of nematode worm. Many other cool article like the articles on Psyblog regarding neuroscientists battling with stroke / bipolar disorder can be found there, so rush on to the encephalon.

Friday, October 05, 2007

I was recently contacted by Hans IJzerman, Editor-in-cheif of in-mind.org, regarding their excellent online article repository. It is basically a social psychology site, containing articles from some of the stalwarts in social psychology like Phillip Zimbardo (BTW, the Phil Zimbardo article is also available on the excellent Situationist blog).

The site, though, requires free registration for reading the articles. One of the articles I found interesting was on evolution of religion, and one of the co-authors was Hans himself. There are plenty of other interesting articles , so head over to have a look.